cGMP is the advance version of the GMP because cGMP states for "current GMP" guidelines those are updated periodically by the pharmaceutical regulatory agencies for GMP inspection.
The term cGMP may be interchangeable with the term GMP, that is because when standards are updated and new regulations are put into place, the new ones become the current, or cGMP. Stating and certifying that the new goods were distributed under newer standards and regulations than those of the GMP. cGMP regulations are very specific and detailed, using the newest technologies available at that time in production. Verifying that every regulation was followed that was set by the standards of GMP. Overall GMP guidelines do not change they are just being added to so that all pharmaceutical products are the best the manufacturers can possibly offer.